Fluid transfer as a mechanism leading to endotension

Endotension as a Rare Complication to Endovascular Abdominal Aortic Aneurysm Repair

Endotension remains an enigmatic rare cause of endovascular abdominal aortic aneurysm repair failure leading to aneurysm growth and/or rupture. We present a patient with a long-standing endotension treated with open reconstruction and graft explantation. We also provide a unique clinical video, which gives a key view of the intrasac operative findings.

Experimental and analytical evaluation on the mass transfer performance of braided stent-grafts

Endoleak and luminal loss related to blood permeation and microthrombus migration remain the main challenges in the aneurysm treatment, although stent-grafts have been widely applied. Stent-grafts provide a boundary to shield blood and microemboli transport, which are correlated with their mass transfer performance. Water permeability of vascular prostheses with woven and knitted structures has been analyzed and documented by many researchers, as well as oxygen and protein transfer. However, it is almost a total lack of blood and microemboli transfer along the braided stent-graft thickness direction. In this research, we provided a methodology for the vascular prostheses mass transfer evaluation. Braided stent-grafts in our former research were conducted on a self-developed testing system to investigate their blood permeability and microthrombus transfer behaviors. The pressure along wall thickness direction can be changed. Analytical models were also established based on pore parameters, making them applicative to different structures. Results revealed that the mass transfer behavior of stent-grafts was positively affected by porosity and pore diameter while negatively influenced by their thickness.

Magnetic Resonance Imaging with a Weak Albumin Binding Contrast Agent can Reveal Additional Endoleaks in Patients with an Enlarging Aneurysm after EVAR

OBJECTIVES/BACKGROUND

To examine the additional diagnostic value of magnetic resonance imaging (MRI) after administration of a weak albumin binding contrast agent in post-endovascular aneurysm repair (EVAR) patients with aneurysm growth with no or uncertain endoleak after computed tomography angiography (CTA).

METHODS

This was a prospective diagnostic cross sectional study carried out between April 2011 and August 2013. MRI was performed in all patients with aneurysm growth≥5 mm after EVAR implantation and no or uncertain endoleak on CTA, or the inability, on CTA, to identify the source of a visible endoleak. All MRI scans were performed on a 1.5 T clinical MRI scanner after administration of a weak albumin binding contrast agent. The presence of endoleaks was assessed by visually comparing pre- and post-contrast T1-weighted images with fat suppression. Post-contrast images were acquired 5 and 15 minutes after contrast administration.

RESULTS

Twenty-nine patients (26 men; 90%) with a median age of 74 years (interquartile range [IQR] 67-76) were included. The median interval between EVAR and MRI was 39 months (IQR 20-50). The median increase in maximum aneurysm diameter during total follow up after EVAR was 11 mm (IQR 6-17). At CTA, 16 patients (55%) had no detectable endoleak, five patients (17%) had suspected but uncertain endoleak, and eight patients had a definite endoleak (28%). On the post-contrast MRI images, endoleak was observed in 24 patients (83%). In all patients with uncertain endoleak on CTA, endoleak was detected with MRI. For type II endoleaks, feeding vessels were detected in 22/23 patients (96%) and these were all, except one, lumbar arteries.

CONCLUSION

In patients with enlarging aneurysms of unknown origin after EVAR, MRI with a weak albumin binding contrast agent has additional value for both the detection and determination of the origin of the endoleak.

Endotension-related aortic sac rupture treated by endograft relining

Endovascular aortic aneurysm repair is an effective alternative to open surgical repair in high risk patient. Endotension is an unpredictable late and rare complication of EVAR. Clinical significance and choice of technique for treatment are controversial. At present, there are no cases of endotension-related aneurysmal sac rupture reported in literature, altough it is frequently associated with late surgical conversion. In this case report is described a case of a patient treated with a first generation Gore Excluder(TM) endograft for abdominal aortic aneurysm, with late aneurysmal sac enlargement without evidence of endoleak and subsequent contained rupture without anemia and shock. We have successfully treated the patient by endovascular procedure, through bilateral percutaneous femoral approach, with relining technique. Three years CT scan follow-up showed the endograft patency and size sac reduction.